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Vehicular Technologies Increasing Connectivity Part 10

Tham khảo tài liệu 'vehicular technologies increasing connectivity part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 15 New Method to Generate Balanced 2n-PSK STTCs P. Viland G. Zaharia and J.-F. Hélard Université européenne de Bretagne UEB Institute of Electronics and Telecommunications of Rennes IETR INSA de Rennes 20 avenue des Buttes de Coesmes F-35708 Rennes France 1. Introduction The use of multiple input multiple output MIMO is an efficient method to improve the error performance of wireless communications. Tarokh et al. 1998 propose the space-time trellis codes STTCs which use trellis-coded modulations TCM over MIMO channels. STTCs combine diversity gain and coding gain leading to a reduction of the error probability. In order to evaluate the performance of STTCs in slow fading channels the rank and determinant criteria are proposed by Tarokh et al. 1998 . In the case of fast fading channels Tarokh et al. 1998 also present two criteria based on the Hamming distance and the distance product. Ionescu 1999 shows that the Euclidean distance can be used to evaluate the performance of STTCs. Based on the Euclidean distance Chen et al. 2001 present the trace criterion which governs the performance of STTCs in both slow and fast fading channels in the case of a great product between the number of transmit and receive antennas. This configuration corresponds to a great number of independent single input single output sub-channels. Liao Prabhu 2005 explain that the repartition of determinants or Euclidean distances optimizes the performance of STTCs. Based on these criteria many codes have been proposed in the previous publications. The main difficulty is a long computing-time to find the best STTCs. Liao Prabhu 2005 and Hong Guillen i Fabregas 2007 use an exhaustive search to propose new STTCs but only for 2 transmit antennas. To reduce the search-time Chen et al. 2002a b advance a sub-optimal method to design STTCs. Thereby the first STTCs with 3 and 4 transmit antennas are designed. Besides another method is presented by Abdool-Rassool et al. 2004 where the first STTCs with 5 .